JP2789088B2 - Method for producing particulate inorganic composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an inorganic composite, and more particularly to a method for producing a particulate inorganic composite having a novel structure, which is particularly useful as a filler for organic substances such as synthetic resins and rubbers. About the method.

[0002]

2. Description of the Related Art In order to improve mechanical strength, an inorganic filler such as silica, alumina or calcium carbonate is blended in a molded article made of an organic material such as synthetic resin or rubber. The mechanical strength of the molded body can be adjusted as necessary by appropriately changing the shape, the blending amount, and the like of such an inorganic filler. In recent years, attempts have been made to improve the thermal characteristics such as the thermal conductivity and the thermal expansion coefficient of a molded article by blending an inorganic filler.
That is, for example, when a synthetic resin is used for encapsulating electronic components such as a metal component or a semiconductor, the thermal characteristics of the metal plate, the metal deposition film, the silicon chip, and the like that constitute these components and the thermal characteristics of the synthetic resin. It is necessary to balance the mechanical properties (particularly the coefficient of thermal expansion). It is also necessary to improve heat dissipation from electronic components such as ICs and transistors having a high-density element. On the other hand, it is also necessary to prevent corrosion of the sealing metal due to a trace amount of impurities contained in the inorganic filler.

Conventionally, as a resin material for a sealing material for electronic parts such as semiconductors, silicone-based, diallyl phthalate-based, epoxy-based resins and the like have been selectively used mainly from the viewpoint of heat resistance. Among these, the most widely used epoxy resin-based sealing materials use crystalline silica, fused silica, and alumina as fillers.

[0004]

However, as apparent from Table 1, the epoxy resin-based sealing material using these fillers has a thermal expansion coefficient (mm / mm / ° C.) and a thermal conductivity (ca).
l / cm · s ° C.) is remarkably different from silicon, which is the central material of semiconductor components, and is not satisfactory in terms of adhesion and heat dissipation.

[0005] Table 1 Thermal expansion coefficient Thermal conductivity Crystalline silica 2.4 × 10 ^-5 50 × 10 ^-4 fused silica 2.1 × 10 ^-5 15 × 10 ^-4 Alumina 14.7 × 10 ^-5 100 × As an inorganic material having a low coefficient of thermal expansion and a high thermal conductivity, aluminum nitride, which is used as a filler for a resin, is used in the case of 10 ^-4 silicon 3.5 to 4 × 10 ^-6 2500 × 10 ^-4 . It is expected that a sealing material similar to silicon can be obtained in terms of thermal characteristics. However, aluminum nitride has a property of reacting with moisture in the air to generate ammonia or reacting with oxygen, and is chemically unstable. In particular, under the conditions of use at high temperature and high humidity, this tendency of aluminum nitride is further promoted, so that it cannot be used as a semiconductor sealing material requiring high reliability even under such severe conditions.

Accordingly, the present invention provides a novel material which has a thermal property close to that of silicon and is chemically stable as an inorganic filler for a resin sealing material for electronic parts such as semiconductors. The main purpose is.

[0007]

The inventor of the present invention has conducted various studies in view of the state of the art as described above, and as a result, it has been found that a particulate inorganic composite having a specific structure can be used for resin sealing of electronic parts such as semiconductors. It has been found that it has extremely excellent properties as an inorganic filler for a stop material, and that this particulate inorganic composite material also exhibits excellent effects as an inorganic filler such as rubber.

That is, according to the present invention, water is added to a mixed solution in which aluminum nitride powder is dispersed in an alcohol solution of alkoxysilane and the mixture is hydrolyzed, and the resulting solid mixed substance is dried, heated, and pulverized. The present invention relates to a method for producing a particulate inorganic composite.

In the method of the present invention, first, a uniform mixed solution in which aluminum nitride powder is dispersed in an alcohol solution of alkoxysilane is prepared. Examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane.Alcohols include methanol,
Examples include ethanol and isopropanol. The concentration of the alcohol solution of alkoxysilane is not particularly limited, but is preferably about 10 to 70% by weight.

As the aluminum nitride powder, an ordinary powder may be used as it is, or after sintering such a powder with or without using a sintering aid, pulverized powder is used. May be used. The average particle size of the aluminum nitride powder is preferably 5 μm or less in order to obtain a uniform dispersion. The amount of aluminum nitride powder with respect to the alcohol solution of alkoxysilane is
Preferably, the content is about 50% by weight.

In order to prepare a uniform mixed solution, aluminum nitride powder is added to an alcohol solution of alkoxysilane, and then the mixed solution is usually stirred while being kept at a temperature of about 25 to 85 ° C. The stirring time varies depending on the concentration of each component of the mixed solution, the temperature at the time of stirring, and the like, and may be a time necessary to obtain a uniform dispersion, and is not particularly limited. It goes without saying that the higher the stirring temperature, the shorter the time.

After completion of the stirring, water is added dropwise, and if necessary, an acid catalyst is added, and the temperature is maintained at about 50 to 90 ° C. to complete the hydrolysis. The time required for the hydrolysis is, for example, about 8 hours at 80 ° C.

After the completion of the hydrolysis, the reaction solution is heated to about 50 to 90 ° C. to remove water, alcohol as a solvent and alcohol generated by hydrolysis. This removal step can be performed continuously with the preceding hydrolysis step.
Next, the obtained solid is dried at about 40 to 150 ° C. This drying step is preferably performed on the high temperature side within the above temperature range in order to shorten the required time. The time required for drying is, for example, about 110 hours at 110 ° C.

The dried solid content is then reduced to 800 to
It is heat-treated at 1200 ° C. and pulverized to a desired particle size to obtain the particulate silica-aluminum nitride composite of the present invention. In the method of the present invention, a particulate inorganic composite in which aluminum nitride is dispersed and contained in a silica glass matrix having a silica purity of 99.5% or more can be obtained depending on the conditions.

[0015]

According to the present invention, the following effects are achieved.

(A) The thermal characteristics of the particulate inorganic composite of the present invention are close to those of silicon. Therefore, when the composite is used as a filler in a resin material for sealing electronic components such as semiconductors, the thermal conductivity and the coefficient of thermal expansion of the sealing material are close to those of silicon. Is improved.

(B) In the particulate inorganic composite of the present invention, the aluminum nitride particles which are unstable in the air are protected, so that the electronic component sealed with the resin containing the inorganic composite has a high temperature and a high humidity. It shows stable characteristics even under conditions.

(C) The particulate inorganic composite of the present invention is useful as a filler for rubber, cement, mortar, brick and the like, in addition to resin.

[0019]

EXAMPLES Examples are shown below to further clarify the features of the present invention. In the following, all “parts” indicate “parts by weight”.

Examples 1 to 6 10 parts of stearic acid were added to a mixture of 100 parts of aluminum nitride powder (average particle size: about 3 μm) and 3 parts of Y ₂ O _3, and the mixture was mixed with ethanol as a dispersion medium in a ball mill for 24 hours. After that, the mixture was dried at 80 ° C., granulated, and
A powder that passed through the mesh was obtained. The obtained powder was placed in a mold and compressed at a molding pressure of 1000 kg / cm ² to obtain a molded body, degreased, and sintered at 1800 ° C. under a normal pressure for 3 hours in a nitrogen stream. Next, the sintered body was pulverized to obtain aluminum nitride having an average particle size of 5 μm.

On the other hand, the aluminum nitride powder obtained above was added to a solution composed of 100 parts of ethanol and 150 parts of tetraethoxysilane @ Si (OC ₂ H ₅ ) ₄ at a predetermined ratio, mixed well, and then stirred. Water was added dropwise below to hydrolyze. The solid formed by the hydrolysis was dried at 90 ° C for 10 hours, and heated to 1200 ° C at a rate of 5 ° C / min to obtain a silica-aluminum nitride composite. Next, this was pulverized to obtain a powder having an average particle diameter of about 6 μm.

The particulate silica-aluminum nitride composite 6 obtained above was added to 100 parts of a composition mainly composed of a cresol novolak epoxy resin and a phenol novolak resin.
8 parts were added to obtain an electronic component sealing resin composition.

Using the obtained resin composition, at a temperature of 18
A test piece having a diameter of 20 mm × 2 mm was formed at 0 ° C. and a pressure of 70 kg / cm ² , and the coefficient of thermal expansion (A: mm / mm / ° C.) was measured with a thermal dilatometer (manufactured by Du Pont). B: cal
/ Cm · s ° C) was measured by a thermal conductivity meter (solution method). Table 2 shows the results.

Comparative Examples 1 to 3 In place of the particulate silica-aluminum nitride composite of Example 1, fused silica having an average particle diameter of about 6 μm (Comparative Example 1)
Except for using crystalline silica (Comparative Example 2) or alumina (Comparative Example 3), three kinds of resin compositions for encapsulating electronic components were prepared in the same manner as in Example 1, and the thermal characteristics were examined. The results are shown in Table 2.

Table 2 Example AlN / SiO2 (A) (B) 185/15 1.0 × 10 ^-5 160 × 10 ^-4 275/25 1.4 × 10 ^-5 140 × 10 ^-4 3 65/35 1.5 × 10 ⁻⁵ 130 × 10 ⁻⁴ 4 55/45 1.6 × 10 ⁻⁵ 110 × 10 ⁻⁴ 5 45/55 1.9 × 10 ⁻⁵ 85 × 10 ⁻⁴ 6 20 / 80 2.1 × 10 ^-5 68 × 10 ^-4 Comparative Example 1-2.3 × 10 ^-5 13 × 10 ^-4 2-2.5 × 10 ^-5 45 × 10 ^-4 3--14.5 × 10 ^-5 75 × 10 ^-4 Examples 7-12 100 parts of isobutanol and tetraethoxysilane @ Si
(OC ₂ H ₅ ) ₄ Add aluminum nitride powder (average particle size 5 μm) at a predetermined ratio to a solution consisting of 65 parts
And then cooled. Water was added dropwise to the obtained homogeneous mixture with stirring, and the mixture was kept at 85 ° C. for 10 hours to completely hydrolyze. The solid formed by the hydrolysis was heated at 90 ° C. for 12 hours to remove water, a solvent (isobutanol) and ethanol produced by the reaction, and then dried at 110 ° C. for 20 hours. Next, the dried product is heated to 1200 ° C. at a rate of 5 ° C./min and maintained at the same temperature for 2 hours to obtain a silica-aluminum nitride composite, which is then cooled and pulverized to obtain an average particle diameter. A powder of about 5 μm was obtained.

The particulate silica-aluminum nitride composite 6 obtained above was added to 100 parts of a composition containing a cresol novolak epoxy resin and a phenol novolak resin as main components.
9 parts were added to obtain a resin composition for sealing electronic parts. Using the obtained composition, thermal characteristics were measured in the same manner as in Examples 1 to 6. Table 3 shows the results.

Comparative Examples 4 to 6 Instead of the particulate silica-aluminum nitride composites of Examples 7 to 12, fused silica having an average particle diameter of about 5 μm (Comparative Example 4), crystalline silica (Comparative Example 5) or alumina ( In the same manner as in Examples 7 to 12 except that Comparative Example 6) was used, 3
Various kinds of resin compositions for encapsulating electronic components were prepared, and their thermal characteristics were examined. The results are shown in Table 3.

Table 3 Example AlN / SiO 2 (A) (B ) 785/15 1.0 × 10 ^-5 145 × 10 ^-4 875/25 1.2 × 10 ^-5 135 × 10 ^-4 9 65/35 1.3 × 10 ⁻⁵ 120 × 10 ⁻⁴ 10 55/45 1.5 × 10 ⁻⁵ 100 × 10 ⁻⁴ 11 45/55 1.8 × 10 ⁻⁵ 70 × 10 ⁻⁴ 12 20 / 80 2.0 × 10 ^-5 65 × 10 ^-4 Comparative Example 4 2.3 × 10 ^-5 13 × 10 ^-4 5 2.5 × 10 ^-5 45 × 10 ^-4 6 15.5 × 10 ^-5 75 × 10 ⁻⁴ Examples 13 to 18 A silica-aluminum nitride composite was obtained in the same manner as in Examples 7 to 12, except that aluminum nitride powder having an average particle diameter of 1.2 μm was used. A resin composition for sealing parts was obtained. Using the obtained composition, thermal characteristics were measured in the same manner as in Examples 1 to 6. Table 4 shows the results.

Table 4 Example AlN / SiO 2 (A) ( B) 13 85/15 0.95 × 10 ^-5 150 × 10 ^-4 14 75/25 1.2 × 10 ^-5 140 × 10 ^-4 15 65/35 1.25 × 10 ⁻⁵ 125 × 10 ⁻⁴ 16 55/45 1.4 × 10 ⁻⁵ 100 × 10 ⁻⁴ 17 45/55 1.7 × 10 ⁻⁵ 70 × 10 ⁻⁴ 18 20 / 80 1.9 × 10 ⁻⁵ 65 × 10 ⁻⁴ Examples 19 to 24 Aluminum Nitride Powder (Average Particle Size: about 1.5 μm) 100
10 parts of stearic acid was added to the mixture, and the mixture was mixed for 24 hours with a ball mill using ethanol as a dispersion medium.
C., dried at 100.degree. C. and granulated to obtain a powder passing through 100 mesh. The obtained powder is put into a mold, and a molding pressure of 1000 kg /
After compressing at ² cm to obtain a compact, degreased
Sintered at 00 ° C for 3 hours under normal pressure. Next, the sintered body was pulverized to obtain an aluminum nitride powder having an average particle size of 5 μm.

In the same manner as in Examples 7 to 12 except that the aluminum nitride powder thus obtained was used, silica
After obtaining the aluminum nitride composite, a resin composition for sealing electronic parts was further obtained. Using the obtained composition, thermal characteristics were measured in the same manner as in Examples 1 to 6. Table 5 shows the results.

Table 5 Example AlN / SiO 2 (A) (B) 1985/15 1.0 × 10 ^-5 155 × 10 ^-4 20 75/25 1.2 × 10 ^-5 145 × 10 ^-4 21 65/35 1.3 × 10 ⁻⁵ 130 × 10 ⁻⁴ 22 55/45 1.5 × 10 ⁻⁵ 110 × 10 ⁻⁴ 23 45/55 1.8 × 10 ⁻⁵ 80 × 10 ⁻⁴ 24 20 The result of / 80 2.0 × 10 ⁻⁵ 70 × 10 ⁻⁴ or more indicates that the particulate inorganic composite according to the method of the present invention exhibits an excellent effect.

Claims (1)

(57) [Claims] 1. A method in which water is added to a mixed liquid in which aluminum nitride powder is dispersed in an alcohol solution of an alkoxysilane and the mixture is hydrolyzed, and the resulting solid mixed substance is dried, heated and pulverized. A method for producing a particulate inorganic composite.